How do you remove mould on the ceiling, and stop it coming back?

Why mould on ceilings is common in Singapore homes

Mould grows where a surface stays damp long enough for spores to settle. In a humid climate, many ceilings stay damp for hours at a time. Most cases come down to one of four causes.

• Humidity. The air holds a lot of moisture all year, and rooms that stay closed, such as a storeroom, are slow to dry.
• Poor ventilation. Bathroom ceiling mould is the most common case. A hot shower fills a small room with steam that has nowhere to go.
• Condensation. When warm, moist air meets a cooler surface, water collects on it and keeps the ceiling slightly wet.
• A leak from above. Water from the flat above, or from the roof, can soak into the ceiling and keep it damp from within.

You can usually manage the first three yourself. A leak keeps feeding water into the ceiling however often you clean, so rule it out first.

Find out if it is a leak first

Mould from steam tends to show up as scattered spots, often near the shower or in corners where air does not move. A leak usually looks different. Watch for:

• a damp patch that spreads or changes shape over days or weeks
• paint that bubbles, flakes or peels
• drips, or water collecting around a light fitting
• stains that appear soon after your upstairs neighbour showers

If you see these signs, the ceiling needs more than cleaning. HDB's guide to ceiling leaks says flat owners are responsible for the upkeep and maintenance of their own flat. For a ceiling leak between two flats, HDB describes the owners engaging a contractor together. The contractor recommends a repair method based on how severe the leak is, and some leaks need more than one method. For leaks from common property, HDB says to contact the Town Council.

Cleaning a ceiling that a leak is still feeding only hides the problem for a while. If you are not sure where the water comes from, a company offering water leak detection and repair can help trace the source. Our guide on what to do about a ceiling leak covers the next steps.

How to clean small patches safely

If the mould covers a small area and you have ruled out a leak, you can usually clean it yourself. Use a cleaner made for mould, follow the label and work from a stable step ladder.

1. Ventilate and protect yourself. Open the window and door. Wear gloves and eye protection, because drips fall towards your face when you work overhead.
2. Switch off nearby fittings. Turn off any light, fan or exhaust fan near the patch at the wall switch, and keep liquid away from it.
3. Test the cleaner first. Try it on a small, hidden spot to check it does not mark or discolour the paint.
4. Wipe, do not dry-brush. Apply the cleaner as the label says, then wipe the mould away with a damp cloth. Dry-brushing can spread spores around the room.
5. Dry the area fully. Leave the window open or run a dehumidifier until the ceiling is completely dry.
6. Check again after a week. If spots return quickly, the moisture problem has not been solved yet.

Ceiling lights and fans are often close to damp spots. EMA's electrical safety advice notes that all homes must have a residual current circuit breaker (RCCB), but switching off before you start and keeping water away from fittings is still the safer habit.

When to repaint or call a professional

Cleaning at home suits light mould on a sound ceiling. Some signs mean you need more than a cloth and a spray bottle.

Repainting comes last. Once the cause is fixed and the ceiling is clean and dry, a painter can cover old stains with an anti-mould paint. Painting over live mould or a damp ceiling tends to bring the spots back. You can find companies offering house painting in the directory.

For heavier mould, you may prefer to hire help. You can compare home cleaning companies and see the prices they publish. The cost depends on the job, such as the size of the area, so ask for a quote that matches your home.

Preventing it coming back

If you only remove mould from ceiling surfaces and leave the damp behind, the spots return. The aim is to keep the ceiling dry.

• Clear the steam. Run the exhaust fan or open the window during and after every shower.
• Keep the bathroom door open. Leave it open after use so the room can dry.
• Dry the air. A dehumidifier helps in rooms that stay closed. Empty the tank regularly.
• Fix leaks quickly. Deal with a leak as soon as you notice it rather than painting over the stain.

Good habits in your flat also protect the home below. HDB's ceiling leak guide includes using non-corrosive detergents and taking care when washing kitchen and bathroom floors among its prevention tips. For more, see our guide to bathroom maintenance.

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